1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp. 4 */ 5 6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 7 8 #include <linux/module.h> 9 #include <linux/mod_devicetable.h> 10 #include <linux/kernel.h> 11 #include <linux/platform_device.h> 12 #include <linux/random.h> 13 #include <linux/hw_random.h> 14 15 static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) 16 { 17 unsigned long *buf; 18 int i, len; 19 20 /* We rely on rng_buffer_size() being >= sizeof(unsigned long) */ 21 len = max / sizeof(unsigned long); 22 23 buf = (unsigned long *)data; 24 25 for (i = 0; i < len; i++) 26 powernv_get_random_long(buf++); 27 28 return len * sizeof(unsigned long); 29 } 30 31 static struct hwrng powernv_hwrng = { 32 .name = "powernv-rng", 33 .read = powernv_rng_read, 34 }; 35 36 static int powernv_rng_remove(struct platform_device *pdev) 37 { 38 hwrng_unregister(&powernv_hwrng); 39 40 return 0; 41 } 42 43 static int powernv_rng_probe(struct platform_device *pdev) 44 { 45 int rc; 46 47 rc = hwrng_register(&powernv_hwrng); 48 if (rc) { 49 /* We only register one device, ignore any others */ 50 if (rc == -EEXIST) 51 rc = -ENODEV; 52 53 return rc; 54 } 55 56 pr_info("Registered powernv hwrng.\n"); 57 58 return 0; 59 } 60 61 static const struct of_device_id powernv_rng_match[] = { 62 { .compatible = "ibm,power-rng",}, 63 {}, 64 }; 65 MODULE_DEVICE_TABLE(of, powernv_rng_match); 66 67 static struct platform_driver powernv_rng_driver = { 68 .driver = { 69 .name = "powernv_rng", 70 .of_match_table = powernv_rng_match, 71 }, 72 .probe = powernv_rng_probe, 73 .remove = powernv_rng_remove, 74 }; 75 module_platform_driver(powernv_rng_driver); 76 77 MODULE_LICENSE("GPL"); 78 MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above"); 79